Adsorption behavior of human plasma fibronectin on hydrophobic and hydrophilic Ti6Al4V substrata and its influence on bacterial adhesion and detachment

Abstract

Biomaterial implant-associated infections, a common cause of medical devices' failure, are initiated by bacterial adhesion to an adsorbed protein layer on the implant material surface. In this study, the influence of protein surface orientation on bacterial adhesion has been examined using three clinically relevant bacterial strains known to express specific binding sites for human plasma fibronectin (HFN). HFN was allowed to adsorb on hydrophobic Ti6Al4V and physically modified hydrophilic Ti6Al4V substrata. Ellipsometric data reveal that the characteristics of the adsorbed protein layers primary depend on solid surface tension and the initial protein concentration in solution. In particular, HFN molecules adopt a more extended conformation on hydrophobic than hydrophilic surfaces, an effect that is more pronounced at low than at high initial protein concentrations. Moreover, the extended conformation of the protein molecules on these surfaces likely facilitates the exposure of specific sites for adhesion, resulting in the higher bacterial-cell attachment observed regardless of the strain considered. Contact angle measurements and the analysis of the number of remaining adhering cells after being subjected to external forces further suggest that both specific and nonspecific (hydrophobic) interactions play an important role on bacterial attachment. This study is the first one to evaluate the influence of surface hydrophobicity on protein adsorption and its subsequent effect on bacterial adhesion using a material whose hydrophobicity was not modified using chemical treatments that potentially led to surface properties changes other than hydrophobicity.

Antibacterial Surface Treatment for Orthopaedic Implants

“…Proteins such as albumin, fibronectin, fibrinogen, laminin, denatured collagens, and some plasma/tissue lipids are the first host substances that interact with the surface structure of the biomaterial [21,27,148]. Reduction of conditional lipid-protein layer formation can be achieved by changing surface physico-chemical characteristics, and/or surface micro-morphology [149].…”

CHAPTER 13. Bacterial Adhesion and Interaction with Biomaterial Surfaces

“…126 Vadillo-Rodriguez et al found that Fn molecules adopt a more extended conformation on hydrophobic than hydrophilic Ti6A14V surfaces and the extended conformation of the proteins facilitates the exposure of specific sites for adhesion, resulting in higher bacterial attachment. 127 We used immuno-AFM (atomic force microscopy) to assess the Fn adsorption/orientation on polyurethane surfaces at the molecular scale. The orientation of Fn adsorbed on polyurethane surface was detected by the monoclonal antibodies (MAb) coupled AFM probes.…”

Enhanced cell growth on nanotextured GaN surface treated by UV illumination and fibronectin adsorption

“…Proteins at the cell-substrate interface play a vital role in mediating the adhesion behavior of cells on synthetic substrates which lack cell binding ligands on the surface [31][32][33][34]. FN is a glycoprotein of the extracellular matrix that binds to integrins.…”